Production of ferric oxide and the recovery of sulphur



.'uiy M, E933. l R BACON ET AL 1,917,684

PRODUCTION OF FERRIC OXIDE AND THE RECOVERY OF SULPHUR Filed Feb. 26, 1930 ATTORNEYS Patented July 11, 1933 laureo STATES PATENT OFFICE RAYMOND l?. BACON, OF BRONXVILLE, AND HENRY T. HOTCHKISS, JR., OF NEW ROCHELLE, NEN YORK; SALT) HOTCHKSS, JR., ASSGNOR TO SAE) BACON' PRODUCTION' OF FERRI() OXIDE AND THE RECOVERY OF SULPHUR Application vfiled February 25, 1930.

This invention relates to the recovery of sulphur and has for an object the provision of an improved process for recovering sulphur from heavy metal sulphide ores. More 'l pait"`iciilaily,r he invention contemplates the provision of an improved process for recoving sulphur from materials containing one or more sulphides of iron, The invention further contemplates the provision of an imi: proved process for treating heavy metal sulphide ores such, for example, as ore containing` sulphides of iron, copper and nichel.

'lhe process of the present invention involves the treatn'ient of ore or other metallurgical raw materials or products contain- .ing pyrites or other sulphides of iron, alone ih combination with sulphides ot other' heavy metals such, for example, as copper and nichel, With sulphuryl chloride forthe 'I purpose of obtaining free sulphur and/or i separating iron from the mass of material undergoing treatment. l

ln carrying out a process in accordance 'with the present invention, a quantity of the fj material to be treated is subjected to the aetlon of sulphnryl chloride under such conditions that free sulphur and ferrous chloride are produced. The operation is so conducted that the sulphur produced is vaporized,

-lcaving a residue containing the ferrous chloride together with chlorides of other heavy metals such as copper and nickel when the sulphides of such metals are present in the material being treated The solid residue is treated to produce ferrie chloride and convert the ferrous chloride and other heavy metal chlorides to oxides. The ferrie chloride is treated to pr duce hydrogen chloride. Tl e hydrogen chloride is subjected to the action of air in the presence of the iron oxide and /or other oxides to produce chlorine.

During the cours-e of the reaction between process.

Serial No. 431,471.

The invention Will be better understood from a consideration of the accompanying liowsheet and the following descriptionv of the application ofthe process to the treatment of ore containing pyrites and sulphides of copper and nickel;

The ore to be treated is subjected to the action of sulphuryl chloride in a reaction chamber under such conditions that ferrous chloride, sulphur dioxide and free sulphur are produced. The operation is so conducted that the sulphur dioxide and sulphur produced are vapor-ized, leaving a residue containing the ferrous chloride together with the chlorides of copper and nickel. A temperature below the boiling point of sulphur may be maintained in the reaction chamber and the sulphur' may be swept from the reaction chamberby means of inert gases introduced with the sulphuryl chloride and/or the sulphur dioxide produced, or a temperature sufhciently high to vaporize the sulphur may be maintained. y

The ore is preferably introduced in a dry, finely divided condition into the interior of a rotary reaction chamber having ore charging means at one end and discharging means at the other end, and which is so' constructed and operated that the ore is gradually moved from the charging end toward the discharge end. Sulphuryl chloride is introduced into the reaction chamber at the end opposite to that at which the ore is introduced and the ore and sulphuryl chloride pass through the reaction chamber in counter-current relationship, the vaporized sulphur being removed from the reaction chamber at a. point near the charging end. Sulphur-yl chloride may be introduced into the reaction chamber as al liquid or as a gas. Liquid sulphuryl chloride 5000 C. It is, therefore, advisable to maintain a temperature of about 5000 C. in at least a portion of the reaction chamber. Such a temperature may be maintained in the chargingend portion of the reaction chamber to insure the passage of all issuing gases through a Zone in which conditions are conducive to a complete reaction.

The process is preferably so controlled that a temperature of about 5000 C. is maintained near the charging end of the reaction chamber, and a temperature of about 2500 C. to 3500 C. is maintained near the discharge end of the reaction chamber. rEhe admission of ore and sulpluu'yl chloride is so regulated that all of the sulphur liberated is vaporized, all of the sulphuryl chloride admitted is consumed and all of the pyrites is converted to ferrous chloride, The sulphur produced vapor-ized and separated from the heavy metal chlorides in the hottest portion of the reaction chamber, and the residue containing the heavy metal chlorides is discharged from the reaction chamber preferably at a temperature of about 3000 C.

Any ferric chloride which is produced in the reaction chamber will be vaporized and swept along with the incoming sulphuryl chloride to meet the entering iron sulphidebearing material. The ferrie chloride will react with the sulphides to form ferrous chloride and sulphur chloride, and the sulphur chloride thus formed will react with the heavy metal sulphides. The reaction between the sulphides and the sulphuryl chloride etc. is exothermic and the desired temperatures may be maintained by the heat developed.

The gases issuing from the reaction chamber are cooled to conoense the sulphur and thus separate the sulphur and sulphur dioxide. The sulphur dioxide is collected and combined with chlorine recovered from the ferrous chloride produced to regenerate sulphuryl chloride.

The residue containing the ferrous chloride and lthe chlorides of copper and nichel is heated in the presence of air to a temperature of about 8000 C. to 4500 C. to form ferrie as ferrie chloride.

oxide and oxides of copper and nickel. The operation is so conducted that the ferrie 'chloride is vaporized. The resulting gases will contain some inert gases and chlorine as well The gases are collected and cooled to condense the ferrie chloride and separate the. chlorine and inert gases. The treatment of the ferrous chloride-bearin g material is preferably conducted in a rotary reaction chamber which is so constructed and arranged that ferrous chloride-bearing material charged into one end portion will move progressively toward the other end portion during its rotation.

The condensed ferrie chloride is vaporized and subjected to the action of water vapor at an elevated temperature in a suitable reaction chamber. The ferrie chloride is hydrolyzed and ferrie oxide and hydrogen chloride are formed, the reaction proceeding according to the following equation:

2FeCl3 -l- 25H20 FegO;s GI-ICl In carrying out the hydrolysis of ferrie chloride, ferrie chloride vapor and superheated steam are introduced together into the reaction chamber in such a manner that intimate mixing will result. The reaction may be conducted conveniently at a temperature of about 3000 C. to 4000 C. Good results may be obtained if the reaction chamber is maintained at a temperature of about 3500 C.

The ferrie oxide will be produced in the form of a line powder which may be permitted to settle out in the reaction chamber. The gases issuing from the chamber contain hydrogen chloride and water vapor and they are passed through a suitable drying apparatus such, for example, as a packed tower having sulphuric acid triclling therethrough to separate the water vapor and produce dry hydrogen chloride.

The dry hydrogen chloride is introduced into a catalytic reaction chamber containing the heavy metal oxides produced with one to seven times its volume of air, depending on the concentration of the hydrogen chloride available. The air is preheated to a temperature above 4200 C. and preferably to a temperature between 5200 C. and 5300 C. If desired, the hydrogen chloride may also be preheated. The ferrie oxide serves as a catalyst for promoting a reaction between the hydrogen chloride and the oxygen of the air.

The catalytic reaction chamber may consist of a tower, or a series of communicating -towers packed with porous material having a very large surface per unit of volume such, for example, as pumice, brick, cinders and the like. The packing material should be of such a nature that it will be inert to the reagents and the products of the reaction. The packing material is covered, mixed or impregnated with the heavy metal oxides which promote a reaction between hydrogen chloride and oxygen. Means are provided for renewing the catalytic mass as its eiiiciency becomes reduced. For this purpose two towers, or two series of communicating towers, which may be used alternately are preferably provided.

The apparatus is so constructed that the mass of catalyst-bearing material may be maintained at a temperature of from 3700 C. to 4000 C. The reaction between the hvdrogen chloride and the oxygen of thepair is exothermic and it may be so controlled as to permit the proper temperature to be maintained. The reaction will proceed at a temperature as low as 2050 C., and a temperature as high as 470 C. may be used advantageously. The reaction involved in this operation does not proceed to completion. The gases issuing from the reaction chamber' will consist of a mixture of hydrogen chloride,

rater vapor and chlorine.

ln view of the fact that the reaction does not readily proceed to completion, it may be desirable to retreat the issuing gases by subjecting them to a drying operation to remove the Water vapor and subsequently passing t-hem through a second reaction chamber'. This procedure may be repeated tivo or three or more times if desired. ln carrying out the reaction between hydrogen chloride and the oxygen of air it is advisable to carefully control the proportions of air and hydrogen chloride utilized in order to avoid excessive dilution of the resulting chlorine gas and in order to avoid the incorporation of excessive amounts of free oxygen in the resulting chlorine gas. y

The gases are Washed with Water to separarate the chlorine and hydrogen chloride. rllhe separated chlorine is dried with sulphuric acid.

The chlorine recovered during the treatment of the heavy metal chlorides with air and the chlorine resulting from the reaction of hydrogen chloride with oxygen are coinbined With the sulphur dioxide produced to regenerate sulphuryl chloride. The reaction between the sulphur dioxide and the free chlorine is preferably conducted at or below normal atmospheric temperatures in the presence of a suitable catalyst such, for example, as activated charcoal. 'l he regenerated sulphuryl chloride may thus be obtained in the form of a liquid. rlhe regenerated sulphuryl chloride is returned to the process for the treatment of additional ore.

a 1 a i rl`he sulphur-ic acid used for drying the hydrogen chloride and chlorine is combined with the Water used for separating the hydrogen chloride and chlorine and the resulting liquid is heat-ed to recover hvdroo'en chloride which 1s returned to the process. The sulphur-1c acid which has been freed from l hydrogen chloride is concentrated and again used for drying purposes. A portion of the steam produced in concentrating the suljrihur acid is utilized for treating the ferrie chloride. The irst fractions obtained during the y concentration of the sulphuric acid will contain hydrogen chloride and the use of these fractions in providing superheated steam for treating the ferric chloride will permit an added recovery of chlorine.

its a result of the treatment of the ferrous chloride-bearing material and the hydrogen chloride with air, considerable quantities ot inert gases such as nitrogen are introduced into the system and must be eliminated to avoid excessive dilution. The inert gases introduced into the system will be mixedwith the chlorine gas Which is recovered and Which is combined with the sulphur dioxide produced to regenerate sulphuryl chloride. These gases Will be eliminated as a result of the production of liquid sulphuryl chloride. rl`he inert gases may be passed through a suitable separator to recover entrained particles or globules of sulphuryl chloride.

rllhe process may be conducted continuously. Ar fresh source of chlorine, in the free state or combined in the form of hydrogen chloride or sulphuryl chloride, may be provided to compensate for chlorine losses due to leakage and the production of nickel and copper chlorides. ln the event that a source of chlorine or hydrogen chloride is provided, an additional source of sulphur dioxide must be provided.

'llhe principal reactions involved inthe process are exothermic and enough .heat is provided that no heat need be supplied from outside sources. Heat generated during the cuir-les of the process may be utilized for carrying out the concentration of the sulphuric acid, vaporization of ferrie chloride and other operations in which temperatures mustbe increased. j

lille claim:

l. The method of treat-ing iron sulphidecaring material which comprises subjecting the material to the action of sulphuryl chloride in such quantity and at such temperature that ferrous chloride and elemental .euh` iur are produced and the sulphur is vaporized in an atmosphere of sulphur dioxide liberated from the sulphuryl chloride, subjectinff'the ferrous chloride to the action of air to term ferrie chloride and ferrie oxide, treating the ferric chloride to form hydrogen chlorine and ferrie oxide, subjecting the hydrogen chloride to the action of air in the presence of the ferrie oxide produced in the treatment of ferrous chloride With air to obtain chlorine, combining the chlorine with sulphur dioxide to form sulphuryl chloride, and utilizing the sulphuryl chloride thus formed for the treatment of additional iron sulphide-bearing material.

2. The method of treating iron sulphidebearing material Which comprises subjecting the material to the action of sulphuryl chloride in such quantity and at such temperature that ferrous chloride and elemental sulphur are produced and the sulphur is vaporized in an atmosphere of sulphur dioxide liberated from the sulphuryl chloride,

chlorine with sulphur dioxide to form sulphuryl chloride, and utilizing the sulphuryl chloride thus formed for the treatment of additional iron sulphide-bearing material.

3. rl`he method of treating iron sulphidebearing material which comprises subjecting the material to the action of sulphuryl chloride in such quantity and at such teinperature that ferrous chloride and elemental t sulphur are produced and the sulphur is vaporized in an atmosphere of sulphur dioxide liberated from the sulphur-yl chloride, subjecting the ferrous chloride to the action of air to forni ferric oxide and to form and vaporize ferrie chloride, condensing` the ferric chloride vapors to eliminate inert gases and any chlorine gas mixed therewith, treating the ferric chloride to form hydrogen chloride and ferrie oxide, subjecting the hydrogen chloride to the action of air in the presence of the ferrie oxide produced in the treatment of ferrous chloride With air to produce chlorine, combining the chlorine With sulphur dioxide to form sulphuryl chloride, and utilizing the sulphuryl chloride thus formed for the treatment of additional iron sulphide-bearing material.

i. The method of treating` ore containing pyrites and sulphides of copper and nickel f which comprises subjecting the ore to the action of sulphuryl chloride in such quantity and at such temperature that a product containing ferrous chloride and chlorides of copper and nichel is formed and elemental l sulphur is produced and vapor-ized, subjecting the metal chloride-bearing product thus formed to the action of an' at an elevated temperature to form ferrie chloride and oxides of iron, copper and nickel, treating the ferrie chloride to form hydrogen chloride and ferrie oxide, subjecting the hydrogen chloride to the action of air in the presence of the oxides of iron, copper and nickel to recover chlorine, combining the chlorine with sulphur dioxide to form sulphuryl chloride, and utilizing the sulphuryl chloride thus formed for the treatment of additional ore.

5. The method of treating iron sulphidebearing material Which comprises subjecting the material to the action of sulphuryl chloride in such quantity and at such temperature that sulphur dioxide, ferrous chloride and elemental sulphur are produced and the sulphur dioxide and sulphur are simultaneously vaporized, subject-ing the ferrous chloride to the action of air to form ferric oxide and to form and vaporize ferrie chloride, condensing the ferric chloride vapors to eliminate inert gases and any chlorine gas mixed therewith, treating the ferrie chloride to form hydrogen chloride and ferrie oxide, subjecting the hydrogen chloride to the action of air in the presence of the ferrie oxide produced in the treatment of ferrous chloride with air to obtain chlorine, combining the chlorine with the sulphur dioxide produced to regenerate sulphuryl chloride, and returning the regenerated sulphuryl chloride to the process for the treatment of additional iron sulphide-bearing material.

In testimony whereof We aliix our signatures.

RAYMGND F. BACON. HENRY T. HOTCHKISS, JR. 

